Nutritional therapies are commonly applied in ill people in order to enhance physical capacity and recovery from stresses due to medical conditions. Many times the recommendations simply include dietary advice regarding the distribution of carbohydrates, proteins, and fats in the overall diet. A more advanced approach is to recommend supplementation of key nutrients that will aid healing and enhance the physical state of the individual. Such nutritional formulations may be termed “dietary supplements,” “functional foods” or “medical foods.” In order to formulate an effective dietary supplement or functional or medical food, an understanding of the scientific basis behind the key ingredients is essential. Once a well-grounded recommendation toward dietary modification is made it can have a powerful influence on the rate of recovery in the individual who is in poor health.
Often, persons who consider themselves to be in good health with a good nutritional status are actually somewhat suboptimal in both parameters, rendering them at risk for developing such medical conditions. Dietary supplements, functional or medical foods developed for improving cardiovascular function may also benefit such persons as cardioprotectors.
In the area of medically recommended supplementation artificial diets have played a key role for many years. Post-surgery, the gastro-intestinal tract of a patient is typically unable to properly digest food for several days. In such cases parenteral nutrition is essential, wherein the patient is given glucose or a carefully formulated mixture of salts, carbohydrates, amino acids, fatty acids, and vitamins. Even after the patient is weaned from parenteral nutrition, enteral nutrition with a similar composition may be established orally or via a feeding tube, or a medical food enteral supplement may be added to his or her diet in order to optimize the types and amounts of nutrients the patient requires and receives.
The most pressing need for improved prevention, rehabilitation and maintenance regimens is in the area of cardiovascular disease, which is the leading cause of death worldwide. It has been projected that one of five persons in the United States has cardiovascular disease. Within this arena, myocardial infarction accounts for more than half a million deaths per year. Furthermore, survivors face a level of morbidity and subsequent disability that affects their medical, social, and of equal importance, economic status. Therefore, surviving the initial acute event of a myocardial infarction leaves patients with a variety of challenges. Such patients may be left in a state of compromised cardiovascular function such as chronic ischemic disease, congestive heart failure or reduced peripheral blood flow.
Congestive heart failure may have a more insidious onset than that following myocardial infarction. Atherosclerosis may gradually lessen circulation to the heart or uncontrolled hypertension may weaken the heart muscle. Another condition, cardiomyopathy, may occur from a variety of causes including ischemia, hypertension or chronic infection. Whatever the cause, these types of cardiovascular disease may present a similar clinical picture and pose the same problems of treatment and maintenance as does myocardial infarction.
Peripheral vascular disease is closely related to cardiovascular disease, in that the same underlying cause, atherosclerosis, may impair circulation to the skeletal muscles, brain or kidneys, interfering with their function. A nutritional supplement that benefits subjects with cardiovascular disease will also benefit these subjects.
Over the past twenty years, cardiac rehabilitation has provided survivors with an increased quality of life. Cardiac rehabilitation programs have continued to change to meet the needs and expectations of these afflicted individuals. An important aspect of successful rehabilitation is a gradual programmed increase in exercise training with an attention to modifying existing cardiac risk factors. The ultimate goal in any cardiac rehabilitation program is the improvement of functional capacity, the lessening of awareness of activity-produced symptoms, the reduction of disability and the modification of known coronary risk factors for the prevention of subsequent cardiovascular events, that is, to provide cardioprotection. Many patients feel strongly that a good quality of life includes the ability to resume their pre-disease activity, if at all possible.
While general nutritional supplementation is the standard mode of therapy as part of a disease management program, a more focused nutritional program can have more specific and powerful benefits. For example glutamine is useful in the treatment of diseases of the liver due to its ability to increase blood flow to the liver (U.S. Pat. No. 6,001,878). Glutamine is also effective at maintaining the immune system. This was shown in a study where there was a lower level of infection in patients following bone marrow transplantation when their parenteral nutritional program was supplemented with glutamine (Calder and Yapoob 1999). Another example is taurine which has a positive inotropic effect on the heart and can be used as a treatment in congestive heart failure. In a clinical trial 4 weeks of taurine supplementation led to a highly significant improvement in dyspnea, palpitation, crackles, edema, and New York Heart Association functional class (Azuma et al 1983).
Several of the vitamins are known to be beneficial in repairing tissue damage and enhancing rehabilitation. Individual patients vary in diet and physiologic needs and thus in the requirement of supplementation. Ideally, each patient could be evaluated for those supplements that are most suboptimal in the diet or for which there is a higher than expected requirement. However, it is impractical to fine-tune supplementation to each patient, and therefore a useful supplement will contain sufficient vitamins to provide adequate daily intake for the majority of prospective patients.
The best therapy for cardiovascular disease is prevention. Hypertension is a prevalent cause of cardiovascular disease. Persistent hypertension is accompanied by left-ventricular hypertrophy and myocardial stiffness. These factors result in left ventricular diastolic dysfunction. Many drugs are marketed to reduce blood pressure, and the current philosophy suggests that combination therapy is preferred to single drug therapy. A nutritional supplement that caused a reduction in blood pressure is desirable.
Thus the need remains to select the best choice of nutrients and the balance of such nutrients as will benefit the majority of subjects both for recovery from cardiovascular disease and for cardioprotection for the prevention of onset or recurrence of cardiovascular disease.